Assertion :The first molecules formed for replicating cells were most probably RNA.
Reason :This was proved by origin of ribozyme in 1987 by T. Cech in Tetrahymena.

The discovery of ribozymes by Thomas Cech of university of Colorado, US showed that RNA is the central participant in the life of cell. He carried out his study on nucleic acid processing and gene expression in a pond living protozoan Tetrahymena thermophila.  He noticed that RNA molecule from this organism could be cut into pieces and spliced. It was a most surprising discovery in 1982 as it was only known that only proteins act as catalysts in all biochemical reactions.